Products in containers, in particular foods, e.g., drinks in plastic or glass bottles, can be investigated by using various physical measurement methods. The absorption of the product at specific wavelengths of light or infrared radiation can be measured, wherein the rotation of polarized light can also be measured. Similarly the absorption of X- or gamma radiation can be measured, wherein here the absorption depends on the atomic weight of the elements present in the product. By means of a high-frequency field it is possible to measure the dielectric constant which, in the case of drinks, depends in particular on the salt content. In addition to these material properties, macroscopic properties, e.g., the fill level of the product in the container or the mass of the product in the container can also be measured. In the German patent application 10 2004 053 567.1 (application date 5 Nov. 2004, Title: Method of establishing the integrity of a product located in a container, our reference 36144-de), a given feature of the product is determined by means of two different physical measurement methods, wherein differences between the values obtained according to both measurement methods of the given feature are an indication of damage to the integrity of the product. The fill level of the product in the container can be ascertained e.g., by means of X-ray absorption and by means of damping of an HF field. Both methods must be calibrated, as the X-radiation absorption depends on the atomic weight, and the damping of the HF field on the dielectric constant, of the product. If the values obtained with both measurement methods do not correspond to the same fill level, this means that either the atomic weight of the elements present in the product or the dielectric constant of the product do not correspond to the predefined values, i.e. to a whole or unadulterated product.
A multisensor camera for quality control is known from DE-A-43 43 058 in which various imaging sensors operating on different physical principles such as b/w and colour cameras, imaging 3D sensors, imaging sensors which operate with penetrating radiation and imaging NIR spectroscopy sensors, are used together. The sensors are arranged so that they cover the same field of vision and corresponding image elements of the sensors relate to identical image elements of the product surface. The signals of the sensors are converted image-by-image, using a classifier, into a group image in which a code is allocated to each image element, corresponding to its membership of one of numerous, previously taught classes. By means of this multisensor camera it is possible to separate out shredded metal and plastic waste from a random refuse stream.
The integrity or unadulterated nature of a product in a container is at present determined by chemical laboratory tests, for which the product is taken out of the container.